Hi every one, working with the GUIUtility RotateAroundPivot I got this weird situation.

when try to center A GUIButton with the Screen.width and the Screen.height and drag the corner of the window to resize it, the button move away from the center but the pivot point remains on the center of the screen, but when I use direct numbers (400 - 40, 300 - 40) the button remains on the center but the pivot not, this is the code:

var rectButton : Rect = Rect(0, 0, 80, 80);
private var refAngle = float;
// With a function to increase the refAngle value
function ONGUI() {
    GUI.matrix = Matrix4x4.TRS(Vectro3.zero, Quaternion.identity, Vector3(Screen.width / 600.0, Screen.height / 600.0, 1));
    GUI.BeginGroup(new Rect(Screen.width / 2 - rectButton.width / 2, Screen.height / 2 - rectButton.height / 2, rectButton.width, rectButton.height));
    GUIUtility.RotateAroundPivot(refAngle, Vector2(40, 40));
    GUI.Box(Rect(0, 0, 80, 80), "Spin");
    GUI.EndGroup();
}

Any help will be very appreciated, for you attention thanks.